Does Cycles GPU Rendering use Single or Double Floating Point Precision?
I chatted and got an answer from someone on the #blendercoders IRC chat. They said that Blender does use single precision floating points. The GeForce cards are going to be the best choice for rendering because they do better at single points than doubles. The Quadro and Tesla lines wouldn't perform as well because they handle double point operations better than singles, and are mostly used in CAD and software that does scientific research. So, the best choice would be to go for the GeForce line because they perform better at single point operations which is what blender uses.